This invention was initially developed for the purpose of analyzing specimens of rock or ore to determine the abundance in the specimen of different specific mineral grains. For clarity of description the invention will be discussed with reference to that particular usage. It should be recognized that the invention is adaptable to other usages in which specimens, samples, or images are to be optically scanned in a systematic manner to identify visually distinct components while generating and processing data indicative of characteristics of one or more such components.
Statistical sampling techniques are often employed in optical scanning operations of the above described kind, particularly where the component areas to be identified and analyzed may be numerous and of small size. Prior systems for conducting this kind of analysis are either manually operated or are essentially automatic in that the operator does not perform such functions as area recognition, scan movement control and data readout and reduction.
Fully automated image analysis systems are usually based on photometric recognition of objects at a plurality of discrete sampling points in the specimen or image or on automatic areal image analysis. These automated optical scanning systems are not well suited to many specific usages including, for example, the mineralogical analysis of complex rock or ore specimens. The ability of automated systems to distinguish and identify certain types of objects, such as mineral grains for example, is at best very limited in relation to that of a human operator.
Certain of the disadvantages of automated scanning systems can be avoided by using manually operated scanning apparatus. Ore specimens, for example, can be scanned by human operators with the aid of a microscope equipped with a stage that is translatable by manual turning of any selected one of a plurality of micrometers. The operator optically scans the specimen along a series of parallel scan lines by turning selected micrometers to produce the scanning motion. The particular micrometer which is used to produce the scanning motion at any given time is dependent on the type of area being scanned at that moment, each of the micrometers being indicative of a different type of component of the image. Thus readings of the several micrometers following scanning of a given line indicates the abundance of the component identified by each micrometer along the scanned line. The micrometer readings may also be manually recorded at transition points in the course of scanning to enable computation of the average size of different mineral grains or the like.
Manual optical scanners of this kind can be more accurate than some of the automatic systems discussed above. This is in part a result of the line integration statistical sampling technique which is inherent in the manual apparatus. Continuous scanning along a line is analagous to making a nearly infinite number of point counts. The manual system also benefits from the superior ability of a human operator to distinguish and identify different components in the specimen or image.
Unfortunately, operation and reading of the micrometers is very time consuming and prone to error. There is also a practical limit on the number of micrometers which can be attached to the translation stage of the microscope thereby making it difficult at best to analyze specimens having a greater number of different areas to be identified and measured. Reduction of the readings taken from the micrometers to obtain the desired information, such as the abundance of various components of the image, may also require at least some time consuming manual arithmetical operations.
Thus fully automated optical scanning systems are subject to object recognition problems when employed for certain purposes. Manual scanning systems are very slow in operation, taxing to operate and error prone and are not well suited for analysis of specimens or images having a large number of different components to be identified.
The present invention is directed to overcoming one or more of the problems set forth above.